Command Language & Python Extensionsfracanalysis.com/pdfs/FRANC3D V7.4 Commands_Python.pdf1 Command...

$: Command Language & Python Extensionsfracanalysis.com/pdfs/FRANC3D V7.4 Commands_Python.pdf1 Command Language & Python Extensions Version 7.4 Fracture Analysis Consultants, Inc Revised:$
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Command Language

& Python

Extensions

Version 7.4

Fracture Analysis Consultants, Inc

www.fracanalysis.com

Revised: April 2021

http://www.fracanalysis.com/

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Table of Contents:

1. Introduction ................................................................................................................................. 4

2. Command File Syntax................................................................................................................. 4 2.1 Commands ............................................................................................................................ 8

2.1.1 AutoGrowth( ) ................................................................................................................ 8 2.1.1.1 sif_params .............................................................................................................. 9

2.1.1.2 growth_params ....................................................................................................... 9

2.1.1.3 growth_plan ......................................................................................................... 11

2.1.1.4 growth_variables .................................................................................................. 12

2.1.1.5 template_params .................................................................................................. 12

2.1.1.6 front_fitting_params ............................................................................................ 12

2.1.1.7 general_analysis_options ...................................................................................... 13

2.1.2 CloseModel( ) .............................................................................................................. 14

2.1.3 ComputeCOD( ) ........................................................................................................... 14 2.1.4 ComputeGrowthParams( ) ........................................................................................... 14

2.1.5 ComputeSif( )............................................................................................................... 14 2.1.6 CrackTractConst( )....................................................................................................... 15

2.1.6.1 CFT index and load case ....................................................................................... 15

2.1.7 CrackTractDelete( ) ..................................................................................................... 15 2.1.8 CrackTractExternalDist( ) ............................................................................................ 15

2.1.9 CrackTractSurface( ) .................................................................................................... 16 2.1.10 CrackTract1DRad( )................................................................................................... 16 2.1.11 CrackTract2DRad( )................................................................................................... 17

2.1.12 FretModelImport( ) .................................................................................................... 17

2.1.13 FretNucleationCycles( ) ............................................................................................. 18 2.1.14 FretNucleationDataImport( ) ..................................................................................... 18 2.1.15 GrowCrack( ) ............................................................................................................. 19

2.1.16 GrowCrackFromFile( ) .............................................................................................. 19 2.1.17 GrowMergeCrack ( ) .................................................................................................. 20

2.1.18 Include( ) .................................................................................................................... 20 2.1.19 InsertFileFlaw( )......................................................................................................... 20

2.1.19.1 flaw_insert_params ............................................................................................. 21

2.1.20 InsertMultFileFlaw( ) ................................................................................................. 22 2.1.21 InsertMultParamFlaw( ) ............................................................................................. 22 2.1.22 InsertParamFlaw( )..................................................................................................... 23 2.1.23 InsertUserBdryFlaw( ) ............................................................................................... 23

2.1.24 InsertUserMeshFlaw( ) .............................................................................................. 24 2.1.25 MapState( )................................................................................................................. 24

2.1.26 OpenFdbModel( )....................................................................................................... 25 2.1.27 OpenMeshModel( ) .................................................................................................... 25 2.1.28 ReadFullGrowthHist ( ) ............................................................................................. 26 2.1.29 ReadGrowthParams ( ) ............................................................................................... 26 2.1.30 ReadResponse( ) ........................................................................................................ 26 2.1.31 RunAnalysis( ) ........................................................................................................... 27

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2.1.32 SaveFdbModel( ) ....................................................................................................... 27

2.1.33 SaveGrowthParams( ) ................................................................................................ 28 2.1.34 SaveMeshModel( ) ..................................................................................................... 28 2.1.35 SetEdgeParameters( ) ................................................................................................. 28

2.1.36 SetGrowthParams( ) ................................................................................................... 29 2.1.37 SetLoadSchedule( ) .................................................................................................... 29 2.1.38 SetMeshingParameters( ) ........................................................................................... 30 2.1.39 SetPrevMeshTool( ) ................................................................................................... 30 2.1.40 SetStatusFile( ) ........................................................................................................... 31

2.1.41 SetTrimRegions( ) ...................................................................................................... 31 2.1.42 SetUnits( ) .................................................................................................................. 31 2.1.43 SetUserExtensionsFile( ) ........................................................................................... 32 2.1.44 SetWorkingDirectory( ) ............................................................................................. 32

2.1.45 SifHistory( ) ............................................................................................................... 32 2.1.46 Submodeler( )............................................................................................................. 33

2.1.47 WriteCOD( ) .............................................................................................................. 34 2.1.48 WriteCrackData( ) ...................................................................................................... 34

2.1.49 WriteFatigueData( ) ................................................................................................... 35 2.1.50 WriteGrowthParams( ) ............................................................................................... 35 2.1.51 WriteSERR( ) ............................................................................................................. 36

2.1.52 WriteSif( ) .................................................................................................................. 36 2.1.53 WriteSifPath( ) ........................................................................................................... 37

2.1.54 WriteSifHistory( ) ...................................................................................................... 38 2.1.55 WriteStdTempData( )................................................................................................. 38

2.2 Example Command File ..................................................................................................... 39

3. Python Module .......................................................................................................................... 42

3.1 Command Converter ........................................................................................................... 42 3.2 Python Module .................................................................................................................... 42

3.2.1 class F3DApp ............................................................................................................... 44

3.2.2 class FemModel ........................................................................................................... 53 3.2.3 class FemResults .......................................................................................................... 59

3.2.4 class Flaw ..................................................................................................................... 61 3.2.5 class CrackData ............................................................................................................ 62

3.2.6 class CrackStep ............................................................................................................ 62 3.2.7 class CrackFront........................................................................................................... 63 3.2.8 class FrontPoint ............................................................................................................ 64

4. Python Crack Growth Extensions ............................................................................................. 67 4.1 Data Access Functions ........................................................................................................ 68

4.2 Specifying a user extension file .......................................................................................... 70 4.3 Example user extension files .............................................................................................. 71

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1. Introduction

This document describes the FRANC3D command language and the Python extensions.

The PyF3D module works with Python versions 2.7.6 - 2.7.14. If your system does not have one

of these versions, you can download (and build) Python yourself (see www.python.org).

Note that the PATH and PYTHONPATH environment variables will likely need to be set for all

the Python modules to work correctly. The folder that contains the franc3d executable and the

PyF3D modules should be added to these environment variables.

2. Command File Syntax

When running FRANC3D using the standard GUI menu and dialogs, a session file is saved that

contains the commands executed through the GUI. A user can play-back these commands to

reproduce their actions or edit the file to execute different or modified commands without using

the GUI.

These session files contain a series of command statements. In command files, lines starting

with '#' are comment lines. Informally, the command statements look something like:

command_a(param_1=value1,param_2="string param")

The syntax diagram for a command files is:

Each parameter value is one of the following types:

command

command file

parm list string

command

value string

parm list

= ( )

,

5

Where the types are defined as:

int

float

string

bool

vec3d

string array

int array

value

float array

bool array

vec3d array

check list

int array array

float array array

6

quoted string

plain string

string

A-Z,a-z,or _

plain string

A-Z,a-z,0-9,_,or -

any character except "

quoted string

" "

any character except '

' '

0-9

int

-

0-9

0-9

float

.

-

0-9

e

E

+

-

0-9

True

False

bool

7

float

vec3d

[ ] , float , float

string

string array

[ ]

,

int

int array

[ ]

,

float

float array

[ ]

,

bool

bool array

[ ]

,

vec3d

vec3d array

[ ]

,

check item

check list

[ ]

,

8

2.1 Commands

The FRANC3D commands and their parameter lists are described here, and an example for each

command is provided.

The command parameter type is given after the parameter name in italics. Note that (req) means

that a parameter is required and (opt) means that a parameter is optional.

2.1.1 AutoGrowth( )

Automatically grow crack(s).

parameters:

model_type = string (req) – model type: ABAQUS, ANSYS or NASTRAN

cur_step = int (req) – current crack growth step number

file_name = single quoted string (req) - base file name

sif_params (opt) – see 2.1.1.1

growth_plan (opt) – see 2.1.1.2

template_params (opt) – see 2.1.1.3

front_fitting_params (opt) – see 2.1.1.4

analysis_options (req) – see 2.1.1.5

example: AutoGrowth (

model_type=ABAQUS,

check item

[ ] 0 , float

1

int array

int array array

[ ]

,

float array

float array array

[ ]

,

9

cur_step=1,

file_name='/models/abaqus_cube/acube_init_crack',

num_steps=5,

step_type=SCONST,

const_step_size=0.1,

check_DKth=true,

maximum_steps=5,

temp_radius_type=RELATIVE,

temp_radius=65,

extrapolate=[[3,3]],

flags=[TRANSFER_BC,NO_CFACE_TRACT,NO_CFACE_CNTCT],

connection_type=MERGE,

executable='abaqus.bat',

command='"abaqus.bat" job=Abaqus_cube_crack_STEP_001

ask_delete=NO -interactive -analysis ')

2.1.1.1 sif_params

parameters:

sif_method = string (opt) - SIF computation method

M_INTEGRAL - use the M-integral (interaction integral) technique (default)

DISP_CORR - use the displacement correlation technique

VCCT - use the virtual crack closure technique

do_therm_terms = bool (opt) - include thermal terms

ref_temp = float (opt) - reference temperature, default = 0.0

do_press_terms = bool (opt) - include crack-face pressure terms

crack_face_press_type = string (opt) - crack-face pressure type

crack_face_press = float (opt) - crack-face pressure

do_crack_face_contact = bool (opt) - include contact pressure terms

correct_mid_side = bool (opt) - correction term for curved crack fronts

large_rotations = bool (opt) - correction term large rigid body type rotation

(initial stress options to be replaced with initial strain)

initial_model_type = string (opt) – initial stress model type

initial_mesh_file = string (opt) – initial stress mesh file name

initial_stress_file = string (opt) – initial stress results file name

initial_stress_step = int (opt) – initial stress results load step

initial_stress_substep = int (opt) – initial stress results load substep

initial_stress_scale = float (opt) – initial stress results scalar multiplier

2.1.1.2 growth_params

parameters:

growth_type = string (opt) - growth computation method:

SUBCRITICAL, QUASI_STATIC

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fem_units = string (opt) – US or SI units:

KSI_IN, PSI_IN, MPA_MM, MPA_M, PA_MM, PA_M

SERR_equiv = bool (opt) – strain energy release rate

SERR_equiv_sign = string (opt) – option for setting sign of K_equiv:

FROM_KI, FROM_KII, FROM_KIII, ALWAYS_POS, ALWAYS_NEG

gamma_II = float (opt) – strain energy release rate mode II factor

gamma_III = float (opt) – strain energy release rate mode III factor

closure_flag = bool (opt) – closure

accelerate = bool (opt) – accelerated integration

constant_time_k = bool (opt) – use constant K value for specified time

extension_type = string (opt) – extension type:

MEDIAN_EXT, CYCLES_EXT, USER_EXT

load_schedule_data = string (opt) – load schedule data

load_schedule_label = string (opt) – load schedule description

growth_model = string (opt) – crack growth rate model

growth_model_label = string (opt) – crack growth rate description

eta_II = float (opt) – factor for Mode II of K_equiv

eta_III = float (opt) – factor for Mode III of K_equiv

retardation_alg = string (opt) – crack retardation model

willenborg_params = float array (opt) – Willenborg model parameters

kink_angle_strategy = string (opt) – crack growth kink angle model

MTS, MSS, GEN, SERR, PLANAR, USER_ANG

quasi_static_n = float (opt) – quasi-static crack growth power

quasi_static_loads = string (opt) – quasi-static crack growth load steps

user_py_file = string (opt) – Python user defined crack growth

aniso_tough_params = float array (opt) – anisotropic toughness values

saved_file_name = string (opt) – file name for saving parameters

load_schedule = string (opt) – file name for load schedule

load_step_map = string (opt) – FE load step map

2.1.1.2.1 load_schedule_data

parameters:

version =

example:

load_schedule_data=[\+

"VERSION: 1",\+

"SCHEDULE (",\+

"REPEAT_COUNT: FOREVER",\+

"NUM_CHILDREN: 1",\+

"TRANSIENT (",\+

"REPEAT_COUNT: 1",\+

"CASES:",\+

"NUM_STEPS: 5",\+

"1 NONE 1 1 0",\+

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"2 NONE 1 1 0",\+

"3 NONE 1 1 0",\+

"4 NONE 1 1 0",\+

"5 NONE 1 1 0",\+

")",\+

")"]

2.1.1.2.2 growth_model

parameters:

version =

example:

growth_model=[\+

"VERSION: 2",\+

"NUM_MODELS: 1",\+

"CYCLES_RATE_TYPE: PARIS",\+

"CYCLES_RATIO_TYPE: NONE",\+

"CYCLES_TEMP_INTERP: TEMP_NONE",\+

"CYCLES_TITLE: ",\+

"CYCLES_DESCRIPTION: 0",\+

"CYCLES_PROP_UNITS: MM|MPA|C|SEC",\+

"C: 1e-11 n: 3 DKth: 0.1 Kc: 100 ",\+

"TIME_RATE_TYPE: NONE"]

2.1.1.2.3 load_step_map

parameters:

version =

example:

load_step_map=[\+

"VERSION: 1",\+

"MAX_SUB: 5",\+

"0 0",\+

"0 0",\+

"0 0",\+

"0 0",\+

"0 0",\+

"LABELS: 5",\+

"5 Load Step 5",\+

"4 Load Step 4",\+

"3 Load Step 3",\+

"2 Load Step 2",\+

"1 Load Step 1"],

2.1.1.3 growth_plan

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num_steps = int (opt) – number of crack growth steps

step_type = string (opt) – type of crack growth increment model

const_step_size = float (opt) – constant crack growth median increment

lin_step_start = float (opt) – linear model crack growth start value

lin_step_inc = float (opt) – linear model crack growth increment

user_step = float array (opt) – user-defined crack growth increment list

check_Kc = bool (opt) – check to see if K > Kc

check_DKth = bool (opt) – check to see if DK < DKth

maximum_steps = int (opt) – maximum number of crack growth steps

maximum_cycles = int (opt) – maximum number of cycles

maximum_time = float (opt) – maximum time

maximum_depth = float (opt) – maximum crack depth

check_HCF_threshold = int (opt) – check against HCF threshold

2.1.1.4 growth_variables

median_step = float (opt) – median crack growth step size

cycles_step = float (opt) – crack growth cycles

time_step = float (opt) – time of crack growth

start_cycle = float (opt) – starting cycle count

start_time = float (opt) – starting time

front_mult = float array (opt) – crack front extension factors

2.1.1.5 template_params

use_templates = bool (opt) – use template flag

temp_radius_type = string (opt) – template radius type

ABSOLUTE, RELATIVE

temp_radius = float (opt) – template radius type

temp_prog_ratio = float (opt) – template progression ratio

temp_num_rings = int (opt) – template number of rings of elements

temp_num_circ = int (opt) – template number of elements around front

temp_max_aspect = float (opt) – template element aspect ratio

temp_simple_interserct = bool (opt) – use simple intersections

2.1.1.6 front_fitting_params

smoothing_method = string array (opt) – smoothing type for each crack front

KINK_EXTEN_POLY - polynomial fit to kink angles and extension

FIXED_ORDER_POLY – polynomial fit through front points

MULTIPLE_POLY – three polynomials fit through front points

CUBIC_SPLINE – cubic-spline fit through front points

MOVING_POLY – moving polynomial fit through front points

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NOFIT_EXTRAP – no fitting but extrapolate ends

HERMITIAN – Hermitian polynomial fit through closed-front points

polynomial_order = int array (opt) – polynomial order for each front

discard = int array array (opt) – discard end points for each front

extrapolate = float array array (opt) – extrapolate curve ends for each front

mult_poly_ratio = int array (opt) – multiple polynomial ratio

retain_all_nodes = bool array array (opt) – retains nodes as geometric points

on the new crack front; only applies to GrowCrackFromFile

2.1.1.7 general_analysis_options

flags = string (req) - list of analysis options:

TRANSFER_BC - transfer boundary conditions from uncracked

mesh (default)

NO_TRANSFER_BC - do not transfer of boundary conditions

CFACE_CNTCT - enforce crack face contact

NO_CFACE_CNTCT - do not enforce crack face contact (default)

CFACE_TRACT - write crack face tractions (default)

NO_CFACE_TRACT - do not write crack face tractions

FILE_ONLY - write analysis files only

CHECK_ONLY - perform a data check analysis only

CONTOUR_INTEGRAL - perform contour integral calculation

(applies to ABAQUS or ANSYS)

front_elem_type = string (opt) - type of elements to place at the crack front:

WEDGE - natural wedge elements (default)

COLLAPSED - collapsed brick, front nodes constrained

BLUNTED - collapsed brick, front nodes unconstrained

connection_type = string (opt) - method to join the submodel and global model:

MERGE - combine coincident nodes (default)

CONSTRAIN - join using constraint equations

CONTACT - insert contact conditions between models

merge_tol = float (opt) – tolerance for merging nodes for local/global connection

global_model = single quoted string (opt) - name of the global model

executable = single quoted string (opt) - path to the analysis executable

command = single quoted string (opt) - analysis command passed to the OS

merge_surf_labels = string array (opt) - labels for the merge surfaces on the submodel

global_surf_labels = string array (opt) - labels for the merge surfaces on the

global model

global_is_master = bool (opt) – global connection surface is master if true

element_series_type = string (opt) – element series identifier

Contact and constraint connections have additional parameters and data.

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2.1.2 CloseModel( )

Close the current model.

example: CloseModel()

2.1.3 ComputeCOD( )

Compute crack-front stress intensity factors.

parameters:

distance = float (req) - distance from the crack front

at_nodes = bool (opt) - compute at nodes rather than geometric points (default = true)

example: ComputeCOD(distance=0.1,

at_nodes=false)

2.1.4 ComputeGrowthParams( )

Compute the crack growth.

parameters:

sif_params => see Section 2.1.1.1: sif_params

growth_params => see Section 2.1.1.2: growth_params

growth_vars => see Section 2.1.1.4: growth_variables

example: ComputeGrowthParams(sif_method=M_INTEGRAL,

growth_type=QUASI_STATIC,

median_step=0.01)

2.1.5 ComputeSif( )

Compute crack-front stress intensity factors.

parameters:


example: ComputeSif(sif_method=M_INTEGRAL,

do_therm_terms=true)

15

2.1.6 CrackTractConst( )

Define or edit constant crack-face tractions.

parameters:

index = int (req) - crack traction index

press = float (req) - constant pressure magnitude

load_case = int (req) - traction load case

set_temp = int (opt) – set temperature for traction load step

constant_temp = float (opt) – constant temperature value for traction load step

loadstep_temp = int (opt) – temperature from prior load step for traction load step

example: CrackTractConst(index=1,

pressure=10.0,

load_case=1)

2.1.6.1 CFT index and load case

All crack surface tractions (CFT) have an internal index. Indexes start at 0; each CFT has

its own index. CFTs are applied in their own load step; the first CFT load_case id should

start at a number that is one higher than the last FE model load step id.

2.1.7 CrackTractDelete( )

Delete a crack-face traction.

parameters:


example: CrackTractDelete(index=1)

2.1.8 CrackTractExternalDist( )

Define or edit external distribution crack-face tractions.

parameters:

model_type = string (opt) – external mesh type


mesh_file = single quoted string (req) - external mesh file name

stress_file = single quoted string (req) - external stress file name

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external_step = int (opt) - external load step ID

external_substep = int (opt) - external load substep ID

stress_scale = float (opt) - external stress factor





example: CrackTractExternalDist(index=1,

mesh_file=’my_dist.fem’,

stress_file=’my_dist.str’,

external_step=1,

load_case=1)

2.1.9 CrackTractSurface( )

Define or edit surface treatment crack-face tractions.

parameters:


dist = float array array (req) - distribution distance/traction pairs


file_name = string (opt) - text file with element face ids




example: CrackTractSurface(index=1,

dist=[[0,10],[0.25,0]],

load_case=2)

2.1.10 CrackTract1DRad( )

Define or edit a 1D radial crack-face traction distribution.

parameters:


axis = int (req) - axis of rotation (x = 1, y = 2, z = 3)

offset = vec3d (req) - axis offset from origin

dist = float array array (req) - distribution distance/traction pairs



17



example: CrackTract1DRad(index=1,

axis=1,

offset=[0,0,1],

dist=[[0,10],[0.25,0]],

load_case=2)

2.1.11 CrackTract2DRad( )

Define or edit a 2D radial crack-face traction distribution.

parameters:


axis = int (req) - axis of rotation (x = 1, y = 2, z = 3)

axial = float array (req) - list of axial locations

radial = float array (req) - list of radial locations

dist = float array array (req) - table of traction values for all radial and axial locations





example: CrackTract2DRad(index=0,

axis=1,

axial=[-0.5,0.0,0.5],

radial=[0.0,1.0],

dist=[[0,1,0],[1,1.25,1]],

load_case=2)

2.1.12 FretModelImport( )

Import fretting data model files.

parameters:

model_type = string (req) – model file type

ABAQUS - ABAQUS .inp file

ANSYS - ANSYS .cdb file

file_name = single quoted string (req) – model file name

results_files = string array (req) – list of results file names

results_lcs = int array (req) – list of load case ids in results

18

contact_pair = string array (req) – contact pair name

results_option = int (req) – read pair of results file or single .dtp file

example: FretModelImport(model_type=ANSYS,

file_name=’C:\temp\uncracked.cdb’,

results_files=['C:\ \fretting test rig\fretting_rig_ls1.str',

'C:\ fretting test rig\fretting_rig_ls2.str'],

results_lcs=[0,1],

contact_pair=[contact_6_6_contact_5_6],

results_option=0)

2.1.13 FretNucleationCycles( )

parameters:

fretting_model_type = string (req) – model file type

FRET_SEQ - equivalent stress model

FRET_GCRIT - critical shear stress model

FRET_SWT - Smith-Watson-Topper model

FRET_RUIZ – Ruiz-Chen model

FRET_MSWT – modified Smith-Watson-Topper (Fatemi-Socie) model

fretting_ param_names = string array (req) – fretting model parameters

fretting_ param_vals = float array (req) – fretting model parameters

do_averaging = string (opt) – do volume averaging of stress / strain

do_add_residual = bool (opt) – add residual stress

rdata = float array array (opt) – residual stress data

rfile_name = string (opt) – residual stress data file name

save_file = string (opt) – file name to save fretting cycles

max_load_step = int array (req) – load step id for maximum load

min_load_step = int array (req) – load step id for minimum load

example:

FretNucleationCycles(fretting_model_type=FRET_SEQ,

fretting_param_names=[scale,ef,c,b,a,rotate,C,B,sf,E,d],

fretting_param_vals=[0.001, 32.4, 7170., 0.0004, 1.125, 0, -0.77, 0.00018,

376.6, 126100,-0.77],

do_averaging=FRET_AVRG_NONE)

2.1.14 FretNucleationDataImport( )

parameters:

fretting_raw_data_file = single quoted string (req) – file name for raw fretting

nucleation data

19

fretting_function_type = int (req) – function type for fitting raw data

POLY_FIT=0; polynomial fit

LM_FIT=1; nonlinear exponential fit

fretting_function_id = int (req) – function id

linear=0; polynomial fit

quadratic=1; polynomial fit

cubic=2; polynomial fit

power law=0; nonlinear exponential fit

power1 law=1; nonlinear exponential fit

power2 law=2; nonlinear exponential fit

exponential=3; nonlinear exponential fit

example:

FretNucleationDataImport(fretting_raw_data_file=‘fret_data.txt’,

fretting_function_type=1,

fretting_function_id=2)

2.1.15 GrowCrack( )

Grow crack front(s).

parameters:



template_params => see Section 2.1.1.5: template_params

fit_params => see Section 2.1.1.6: front_fitting_params

file_name = string (opt) - file name

example: GrowCrack(sif_method=M_INTEGRAL,

median_step=0.1,

temp_radius_type=ABSOLUTE,

temp_radius=0.05,

discard=[[0,0]],

extrapolate=[[3,3]])

2.1.16 GrowCrackFromFile( )

Grow crack from a file.

parameters:

read_file = single quoted string (req) - file name of new front points



20

file_name = single quoted string (opt) - file name

example: GrowCrackFromFile(temp_radius_type=ABSOLUTE,

temp_radius=0.05,

read_file='abaqus_cube/small_step.frt'))

2.1.17 GrowMergeCrack ( )

Grow and merge coplanar crack fronts.

parameters:





file_name = string (opt) - file name

fit_points = vec3d array (opt) – list of new fitted crack front points

old_points = vec3d array (opt) – list of current crack front points

norms = vec3d array (opt) – list of crack front normals

frt_idx = int array (opt) – list of crack front ids

frt_ord = bool array (opt) – list of crack front ordering

example: GrowMergeCrack(sif_method=M_INTEGRAL,

median_step=0.1,

temp_radius_type=ABSOLUTE,

temp_radius=0.05,

fit_points=[[1,0,0],[2,0,0],[3,0,0]],

old_points=[[.1,0,0],[.2,0,0],[.3,0,0]],

norms=[[0,0,1],[0,0,1],[0,0,1]],

frt_idx=[1,0],

frt_ord[true,true])

2.1.18 Include( )

Include a file; only available in NO_GUI mode.

parameters:

flags = string array (opt) – INTERACTIVE, NATIVE, ABAQUS, ANSYS, NASTRAN

file_name = single quoted string (req) - file name

2.1.19 InsertFileFlaw( )

21

Insert a flaw from a .crk file. Note that flaw orientation and template options are defined in .crk

files. Parameters for this command, if specified, will override the values in the file.

parameters:

flaw_insert_params => see Section 2.1.19.1

file_name = single quoted string (req) - name of a flaw (.crk) definition file

example:

InsertFileFlaw(

file_name=’my_flaw.crk’,

translation=[0,0.1,0],

radius=0.025)

2.1.19.1 flaw_insert_params

parameters:

rotation_axes = int array (opt) - ordered list of up to three rotation

axes (x = 1, y = 2, z = 3)

rotation_mag = float array (opt) - ordered list of up to three rotation magnitudes

translation = vec3d (opt) - translation vector

local_x_axis = vec3d (opt) – unit x-vector to define rotation

local_y_axis = vec3d (opt) - unit y-vector to define rotation

refinement_level = int (opt) - number of times the flaw patches will be

recursively subdivided

do_template = bool (opt) – true if template used (default = true)

radius = float (opt) - crack-front template radius

progression_ratio = float (opt) - crack-front template element size progression

ratio (default = 1)

num_rings = int (opt) - number of element rings in the crack-front template (default = 3)

num_circ = int (opt) - number of element inserted circumferentially about a

crack-front (default = 8)

max_aspect_ratio = float (opt) - maximum allowable aspect ratio for

crack-front elements (default = 3.0)

simple_ints_only = bool (opt) - if true crack-front templates intersect free surfaces only

if the crack-front meets the surface at nearly a right angle,

otherwise the template terminates within the body

(default = false)

ref_node= int (opt) – node ID for translation

bi_material_flag = bool (opt) – indicates crack is in bi-material interface

bi_material_angle = float (opt) – angle where crack pops out of interface

22

2.1.20 InsertMultFileFlaw( )

Insert multiple flaws from .crk files. The .crk files are read and combined into a single .crk file

that is then inserted using the InsertFileFlaw() command.

parameters:

file_names = quoted string array (req) - names of a flaw (.crk) definition files

example:

InsertMultFileFlaw(

file_names=['crack_1.crk','crack_2.crk'])

2.1.21 InsertMultParamFlaw( )

Insert multiple parameterized flaws.

parameters:

flaw_type = string array (req) - list of flaw types:

CRACK - zero volume crack

VOID - finite volume void

crack_type = string array (req if flaw_type=CRACK) - list of crack types:

ELLIPSE - elliptical crack

THRU - through the thickness crack

CENTER - center crack

LONG - long shallow crack

NONE - place holder for void types

void_type = string array (req if flaw_type=VOID) - list of void types:

ELLIPSOID - ellipsoidal flaw

NONE - place holder for crack types

flaw_params = float array array (req) - list of lists of flaw size parameters

flaw_insert_params array => see Section 2.1.19.1

example:

InsertMultParamFlaw(

flaw_type=[CRACK,CRACK],

crack_type=[EMESH,EMESH],

flaw_params=[[0.1,0.1],[0.15,0.15]],

rotation_axes=[[1],[1]],

rotation_mag=[[90],[90]],

translation=[[0,0.1,1],[0,-0.15,1]],

radius=[0.02,0.03])

23

2.1.22 InsertParamFlaw( )

Insert a parameterized flaw.

parameters:

flaw_type = string (req) - flaw type:

CRACK - zero volume crack

VOID - finite volume void

crack_type = string (req if flaw_type=CRACK) - crack types:

EMESH - elliptical crack

THRU - through the thickness crack

CENTER - center crack

LONG - long shallow crack

RING - double front ring crack

USER - user-defined boundary points crack

UMESH - user-defined mesh crack

void_type = string (req if flaw_type=VOID) - void types:

ELLIPSOID - ellipsoidal flaw

flaw_params = float array (req) - list of flaw size parameters


example:

InsertParamFlaw(

flaw_type=CRACK,

crack_type=EMESH,

flaw_params=[0.15,0.15],

rotation_axes=[1],

rotation_mag=[90],

translation=[0,-0.15,1],

radius=0.03)

2.1.23 InsertUserBdryFlaw( )

Insert a user-defined-boundary flaw.

parameters:

points = Vec3D array (opt) – boundary points

front_flags = int array (opt) – boundary point front flag

file_name = quoted string (opt) – file with boundary points

num_smooth = int (opt) – number of points if smoothing and reparametrizing


24

example:

InsertUserBdryFlaw(

points=[[3.642,5.0,10.054],\+

[3.645,5.0,9.984],\+

[3.650,5.0,9.910],\+

[3.9,5.0,10.14]],

front_flags=[1,1,1,0],

radius=0.078)

2.1.24 InsertUserMeshFlaw( )

Insert a user-defined-mesh flaw.

parameters:

flaw_type = string array (opt) – default is CRACK

mesh_file = quoted string (req) - name of a surface mesh file

front_groups = string array (opt) – crack front node sets in mesh file

front_points = Vec3D array (opt) – crack front points

scaling = float (opt) – scale factor


example:

InsertUserMeshFlaw(

flaw_type=CRACK,

mesh_file='surf_mesh_half_penny.cdb',

front_groups=[CRACK_FRONT],

rotation_axes=[1],

rotation_mag=[-90],

translation=[4,5,10.05],

radius=0.06)

2.1.25 MapState( )

Map material state variables between the previous and the current model – is not currently

implemented.

parameters:

flags = string array (req) - list of state variables to map:

TEMP - nodal temperatures

DISP - nodal displacements

STRESS - nodal stresses

25

STRAIN - nodal strains

example:

MapState(

flags=[DISP,STRESS,STRAIN])

2.1.26 OpenFdbModel( )

Open a FRANC3D database (.fdb) file.

parameters:

file_name = single quoted string (req) - .fdb file name

orig_mesh_file = single quoted string (opt) - name of original, uncracked, mesh model

extra_file = single quoted string array (opt) - list of names of extra (load case) files

mesh_file = single quoted string (req) - name of current crack step mesh model

resp_file = single quoted string (opt) - name of current crack step FEM results

global_file = single quoted string (opt) - name of original global mesh portion

example:

OpenFdbModel(

file_name=’my_cracked_model.fdb’,

orig_mesh_file=’uncracked_mesh.cdb’,

mesh_file=’my_cracked_model.cdb’,

resp_file=’my_cracked_model.dtp’)

2.1.27 OpenMeshModel( )

Open an FEM mesh file.

parameters:

model_type = string (req) - type of file to read:

ABAQUS - ABAQUS .inp file

ANSYS - ANSYS .cdb file

NASTRAN - NASTRAN .bdf file

file_name = single quoted string (req) - mesh file name

global_name = single quoted string (opt) - mesh file name

extra_files = single quoted string array (opt) - list of names of extra load case files

retained_nodes = int array (opt) – list of retained node ids

retained_nodes_file = single quoted string (opt) – retained nodes list file name

retain_old_fronts = bool (opt) – retain crack front nodes from step to step

26

ansys_exe = single quoted string (opt) – ANSYS executable

ansys_lic = string (opt) – ANSYS license type string

retain_auto_cut_surf = string (opt) – retain the cut-surface nodes and facets

example:

OpenMeshModel(

model_type=ANSYS,

file_name=’my_mesh.cdb’)

2.1.28 ReadFullGrowthHist ( )

Read a full crack growth history file.

parameters:

file_name = single quoted string (req) – crack growth history file name

example:

ReadFullGrowthHist(file_name=’history.fcg’)

2.1.29 ReadGrowthParams ( )

Read a crack growth parameters file.

parameters:

file_name = single quoted string (req) – crack growth parameters file name

example:

ReadGrowthParams (file_name=’my.cgp’)

2.1.30 ReadResponse( )

Read a response file.

parameters:

file_name = single quoted string (req) - response file name

example:

27

ReadResponse(

file_name=’my_results.dtp’)

2.1.31 RunAnalysis( )

Run an analysis

parameters:


file_name = single quoted string (req) - response file name

general_analysis_options (req) – see Section 2.1.1.7

example:

RunAnalysis(model_type=”ABAQUS”,

file_name='abaqus_cube/my_crack_model',


merge_tol=0.0001,

executable='abaqus',

command='abaqus job=junk_full -interactive -analysis ',

global_model='abaqus_cube/my_cube_global.inp',

merge_surf_labels=[CUT_SURF],

global_surf_labels=[C_SURF])

2.1.32 SaveFdbModel( )

Save a FRANC3D database (.fdb) file.

parameters:

file_name = single quoted string (req) - .fdb file name

mesh_file_name = single quoted string (opt) - file name for the mesh model

rslt_file_name = single quoted string (req) - file name for the FEM results

global_file_name = single quoted string (opt) - file name for the global mesh

anaysis_code = string (req) - analysis code:

ABAQUS, ANSYS, or NASTRAN

flags = string array (opt) - list of analysis option flags (see Section 2.1.1.7)

example:

SaveFdbModel(

file_name=’my_model.fdb’,

28

mesh_file_name=’my_model.cdb’,

rslt_file_name=’my_model.dtp’,

analysis_code=ANSYS)

2.1.33 SaveGrowthParams( )

Save a crack growth parameters file.

parameters:

file_name = single quoted string (req) – crack growth parameters file name

example:

SaveGrowthParams (file_name=’my.cgp’)

2.1.34 SaveMeshModel( )

Save a FEM mesh file.

parameters:

file_name = single quoted string (req) - mesh file name

model_type = string (req) - analysis code:

ABAQUS, ANSYS, or NASTRAN

flags = string array (opt) - list of analysis option flags (see Section 2.1.1.7)

example:

SaveMeshModel(

file_name=’my_model.cdb’,

model_type=ANSYS)

2.1.35 SetEdgeParameters( )

Set parameters for edge extraction.

parameters:

kink_angle = float (opt) - kink edge angle threshold

do_planar_seed = bool (opt) - use a seed growth algorithm to find planar regions

planar_angle = float (opt) - angle threshold for planar regions

29

planar_facets = int (opt) - minimum number of facets in planar regions

retain_lines = Vec3D array (opt) – end points of geometry lines to retain

retain_infinite_extent = bool array (opt) – flags indicate geometry lines infinitely long

retain_tolerance = float array (opt) – tolerance for each line

example:

SetEdgeParameters(

do_planar_seed=True,

planar_angle=178,

planar_facets=5)

2.1.36 SetGrowthParams( )

Set parameters for crack growth.

parameters:

growth_params => see Section 2.1.1.2

example:

SetGrowthParams(

growth_type=QUASI_STATIC,

load_step_map=["VERSION: 1","MAX_SUB: 2","0 0",

"0 0","LABELS: 2","2 Load Step 2",

"1 Load Step 1"],

kink_angle_strategy=MTS,

quasi_static_n=2,

quasi_static_loads=["NUM_STEPS: 2","1 FINAL 1 1 0",

"2 FINAL 1 1 0"])

2.1.37 SetLoadSchedule( )

Set a load schedule from a file: DARWIN mission format file.

parameters:

file_name = single quoted string (req) – load schedule file name

example:

SetLoadSchedule (file_name=’my.txt’)

30

2.1.38 SetMeshingParameters( )

Modify meshing parameters.

parameters:

max_gen_elems = int (opt) - maximum number of elements that will be generated

surf_refine_bdry_factor = float (opt) - boundary refinement factor for surface meshing

surf_near_bdry_factor = float (opt) - near boundary node factor for surface meshing

optimal_sphere_factor = float (opt) - optimal sphere size factor for volume meshing

optimal_size_factor = float (opt) - optimal octtree size factor for volume meshing

volume_refine_factor = float (opt) - optimal octtree refinement factor for

volume meshing

all_planar_surf_meshing = bool (opt) - force planar surface meshing

do_surface_smoothing = bool (opt) - surface smoothing flag

do_coarsen_crack_mouth = bool (opt) - coarsen crack mouth flag

do_surface_refinement = bool (opt) - surface element refinement flag

max_vol_restarts = int (opt) - maximum number of volume meshing restarts

volume_meshing_method = string (opt) - meshing code:

FRANC3D, ABAQUS, or ANSYS

ansys_executable = string (opt) - ANSYS executable for meshing

ansys_license = string (opt) - ANSYS license type

abaqus_executable = string (opt) - ABAQUS executable for meshing

example:

SetMeshingParameters(

do_surface_refinement=True,

max_vol_restarts=3)

2.1.39 SetPrevMeshTool( )

Set previous mesh and results. This command will work with the MapState command.

parameters:

fem_model = FemModel (req) – pointer to FemModel

fem_results = FemResults (req) – pointer to FemResults

example:

SetPrevMeshTool(fmodel,fresults)

31

2.1.40 SetStatusFile( )

Set a status file. File records success or error status.

parameters:

file_name = single quoted string (req) – status file name

example:

SetStatusFile (file_name=’my_status.txt’)

2.1.41 SetTrimRegions( )

Specify the ID's of regions into which crack will not grow. The crack will be trimmed at the bi-

material interface.

parameters:

region = int array (req) - list of region ids

example:

SetTrimRegions(

regions=[3])

2.1.42 SetUnits( )

Specify the FEM units.

parameters:

model_length = string (opt) – unit for model length: MM, M, INCH

model_stress = string (opt) – unit for model stress (modulus): MPA, PA, PSI, KSI

temperature = string (opt) – unit for model temperature: C, F

DARWIN_units = string (opt) – unit for DARWIN: US, SI

example:

SetUnits(

model_length=INCH,

model_stress=PSI,

temperature=F)

32

2.1.43 SetUserExtensionsFile( )

Set user defined Python extensions file.

parameters:

file_name = single quoted string (req) – Python extensions file name

flags = string array (opt) – flags:

USER_INITIALIZE,

USER_NEW_POINT,

USER_KINK_ANG,

USER_CYCLES_ RATE,

USER_TIME_ RATE,

USER_START_STEP,

USER_END_STEP

example:

SetUserExtensionsFile (file_name=’my_user_growth.py’,

flags=[USER_INITIALIZE,USER_NEW_POINT,USER_KINK_ANG])

2.1.44 SetWorkingDirectory( )

Set the work directory. The path separator for Windows and Linux are different.

parameters:

directory = single quoted string (req) – folder path

example:

SetWorkingDirectory (directory=’/home/work’)

SetWorkingDirectory (directory='C:\user\ansys_models')

2.1.45 SifHistory( )

Compute the SIF history.

parameters:

flags = string array (opt) – SIF history flags: PLANE, INTERACTIVE

path_type = string (opt) – SIF history path type

const_n_dist = float (opt) – normalized distance to compute SIFs

near_n_dist = float (opt) -

33

do_smooth_Ks = bool (opt) -

Ks_poly_order = int (opt) -

do_least_squares = bool (opt) -

poly_order = int (opt) -

min_n_dist = float (opt) -

max_n_dist = float (opt) -

min_smooth_n_dist = float (opt) -

max_smooth_n_dist = float (opt) -

plane_normal = Vec3D (opt) -

plane_point = Vec3D (opt) -

start_type = string (opt) – set start type (point or length)

start_point = Vec3D (opt) – set starting crack point (origin)

start_length = float (opt) – set starting crack length

start_step = int (opt) – set starting crack step id

start_front = int (opt) – set starting crack front id

growth_data_file = string (opt) – crack growth data file name

sif_files = string array (opt) – list of SIF history files

example:

SifHistory(start_front=1)

2.1.46 Submodeler( )

Divide the FE model into local and global portions.

parameters:

flags = string array (opt) – submodeler flags:

INTERACTIVE,

NATIVE,

ABAQUS,

ANSYS,

GLOBAL_ONLY,

SUBMODEL_ONLY,

DARWIN


orig_file_name = single quoted string (req) – input FE model

elem_file_name = single quoted string (req) – element id list file

submodel_file_name = single quoted string (opt) – local submodel file name

global_file_name = single quoted string (opt) – global portion file name

extra_files = single quoted string list (opt) – extra load case file names

elem_groups = string list (opt) – list of element groups

34

example:

Submodeler(

model_type=ABAQUS,

orig_file_name='Abaqus-Cube.inp',

submodel_file_name='Abaqus-Cube_LOCAL.inp',

global_file_name='Abaqus-Cube_GLOBAL.inp',

elem_file_name='Abaqus-Cube_RETAINED_ELEMS.txt',

elem_groups=[“local_elems_a”,”local_elems_b”])

2.1.47 WriteCOD( )

Generate a file containing crack-front crack opening displacement data.

parameters:

file_name = single quoted string (req) - output SIF file name

crack_step = int (opt) - ID (index) of the crack step

front_id = int (opt) - ID (index) of the crack front (0 .. n-1), default = 0

load_step = int (opt) - ID (index) of the load step

load_substep = int (opt) - ID (index) of the load substep

flags = string array (opt) - array of output options:

SPACE - use spaces as delimiters

TAB - use tabs as delimiters (default)

COMMA - use commas as delimiters

COD - include crack opening displacements

CSD - include crack sliding displacements

CTD - include crack tearing displacements

KI - include mode one stress intensity factors

KII - include mode two stress intensity factors

KIII - include mode three stress intensity factors

CRD - include crack-front Cartesian coordinates

DCCRD - include COD evaluation point coordinates

AXES - include crack-front local coordinate axes

MODULI - include the elastic modulus at the evaluation points

example:

WriteCOD(

file_name=’sif_data.sif’,flags=[TAB,COD,CSD,CTD,CRD,DCCRD])

2.1.48 WriteCrackData( )

35

Generate a file containing predicted crack growth data.

parameters:

file_name = single quoted string (req) - output file name

example:

WriteCrackData(

file_name=’crack_info.dat’)

2.1.49 WriteFatigueData( )

Generate a file containing crack-front crack opening displacement data.

parameters:


step = int (opt) - ID (index) of the crack step

front = int (opt) - ID (index) of the crack front (0 .. n-1), default = 0

point = int (opt) - ID (index) of the load step





CYCLES - include cycles

SIFS - include SIFs

SEQUENCE - include load sequence

STEPS - include steps

SURFACE - include surface data

PATH - include path data

KMAX - include Kmax

KMIN - include Kmin

DK - include delta K

example:

WriteFatigueData(

file_name=’ftg_data.fcg’

flags=[TAB,CYCLES])

2.1.50 WriteGrowthParams( )

Generate a file containing crack-growth data.

36

parameters:

file_name = single quoted string (req) - output file name

front_id = int (opt) – crack front id

flags = see flags in 2.1.52

example:

WriteGrowthParams(

file_name=’growth_params.dat’)

2.1.51 WriteSERR( )

Generate a file containing strain energy release rate data.

parameters:







example:

WriteSERR(

file_name=sif_data.sif

flags=[TAB,XYYY,GI])

2.1.52 WriteSif( )

Generate a file containing crack-front fracture parameters and data.

parameters:








37



KI - include mode one stress intensity factors

KII - include mode two stress intensity factors

KIII - include mode three stress intensity factors

J - include J-integral values

T - include T-stress values

TEMP - include temperature values

CRD - include crack-front Cartesian coordinates

AXES - include crack-front local coordinate axes

ANGLE - include the predicted kink angle

DIR - include the normalized predicted propagation direction

REVERSE - reverse the ordering of the values

EXT -

FULL_STEP - write all crack growth data

ALL_STEPS - write all crack growth steps

GI - include mode one energy release rate

GII - include mode two energy release rate

GIII - include mode three energy release rate

COD - include crack opening displacement

CSD - include crack slidng displacement

CTD - include crack tearing displacement

DCCRD - include crack displacement point coordinates

MODULI - include elastic modulus

DARWIN - write Darwin files

example:

WriteSif(


crack_step=4,

load_step=2,

flags=[TAB,KI,KII,KIII,CRD],

correct_mid_side=True,

do_therm_terms=true,

do_press_terms=true)

2.1.53 WriteSifPath( )

Generate a file containing SIF path history data.

parameters:



38



path_type = string (opt) - path type


example:

WriteSif(


load_step=3,

path_type=CLOSEST,

flags=[TAB,XYYY,KI,KII,KIII])

2.1.54 WriteSifHistory( )

Generate a file containing SIF path history data.

parameters:




geometry_name = single quoted string (opt) – geometry file name

example:

WriteSifHistory(

file_name=sif_hist.sif)

2.1.55 WriteStdTempData( )

Generate a file containing the ID's and coordinates of nodes in the crack-front template.

parameters:

file_name = string (req) - output file name

example:

WriteStdTempData(

file_name=template_info.dat)

39

2.1.56 IntegrateStep( )

Integrate cycles for a step of crack growth.

parameters:

example:

IntegrateStep()

2.1.57 GetIntegrationResults( )

Get the integration results.

parameters:

example:

GetIntegrationResults()

2.2 Example Command File

Command files are typically given a .f3d or .log extension. They can be used within the GUI

using the File - Playback menu option. They can also be used in batch mode from the command

line as in:

C:\f3d\franc3d.exe -batch input_commands.f3d

An example command file might look like this:

---------------------------------

# FRANC3D Version 7.4

40

SetWorkingDirectory(

directory='C:\Abaqus_base')

OpenMeshModel(

model_type=ABAQUS,

file_name='Abaqus-Cube.inp',

retained_nodes_file='Abaqus-Cube_RETAINED.txt')

InsertFileFlaw(

file_name='Cube_Crack.crk')

RunAnalysis(

model_type=ABAQUS,

file_name='Abaqus_cube_crack.fdb',




command='"abaqus.bat" job=Abaqus_cube_crack ask_delete=NO -interactive -analysis ')

ComputeSif()

SetUnits(

model_length=MM,

model_stress=MPA,

temperature=C)

SetGrowthParams(

growth_type=SUBCRITICAL,

fem_units="MM|MPA|C|SEC",

load_schedule_data=[\+

"VERSION: 1",\+

"SCHEDULE (",\+

"REPEAT_COUNT: FOREVER",\+

"NUM_CHILDREN: 1",\+

"SIMPLE_CYCLIC (",\+

"REPEAT_COUNT: 1",\+

"R: 0",\+

"KMAX:",\+

"ONE_STEP: 1 0 1 1 0",\+

")",\+

")"],

growth_model=[\+

"VERSION: 2",\+

"NUM_MODELS: 1",\+

"CYCLES_RATE_TYPE: PARIS",\+

"CYCLES_RATIO_TYPE: NONE",\+

41

"CYCLES_TEMP_INTERP: TEMP_NONE",\+

"CYCLES_TITLE: ",\+

"CYCLES_DESCRIPTION: 0",\+

"CYCLES_PROP_UNITS: MM|MPA|C|SEC",\+

"C: 1e-010 n: 3 DKth: 0.1 Kc: 100 ",\+

"TIME_RATE_TYPE: NONE"],

load_step_map=["VERSION: 1","MAX_SUB: 1","0 0","LABELS: 1","1 Load Step 1"],

kink_angle_strategy=MTS)

GrowCrack(

median_step=0.1,

cycles_step=1000,

front_mult=[1],


temp_radius=65,


AutoGrowth(

model_type=ABAQUS,

cur_step=1,

file_name='Abaqus_cube_crack',

num_steps=5,

step_type=SCONST,


check_Kc=true,

check_DKth=true,

maximum_steps=5,


temp_radius=65,

extrapolate=[[3,3]],




command='"abaqus.bat" job=Abaqus_cube_crack_STEP_001 ask_delete=NO -interactive -

analysis ')

WriteSifPath(

file_name='k_vs_a.sif',

load_step=1,

flags=[TAB,A,KI,KII,KIII,CRD])

---------------------------------

42

3. Python Module

The Python module has extensions that mirror the commands described in Section 2. It allows

the user to write more elaborate Python scripts that include these commands.

3.1 Command Converter

The commands described in Section 2 can be converted to Python commands using the Fcl2Py

executable. This program requires one argument, which is the command file name. It reads the

commands from the file, converts them to the equivalent Python commands, and then writes this

information to stdout, which can be piped to a file.

For example:

C:/examples/Fcl2Py.exe session01.log > ses01.py

3.2 Python Module

The PyF3D.dll (or PyF3D.pyd) must be imported into Python. The module requires the

Vec3D.pyd (or Vec3D.py) module, which is distributed with the PyF3D module. The PyF3D

module is linked against Python libraries. The current Version 7.4 module is linked with Python

2.7.

A typical Python script would start by importing the “sys” module and appending the path to the

PyF3D.dll file before importing the PyF3D module:

import sys

sys.path.append("C:\\FRANC3D")

import PyF3D

import Vec3D

Note that for MSWindows, PyF3D.pyd is the same as PyF3D.dll; just the extension is changed.

The PATH and PYTHONPATH might also need to be set as noted in the Introduction.

In Windows, the environment variables can be set for a user or for the system. Figure 3.1 shows

the system-variable PATH and PYTHONPATH setting. Some software programs will only use

the system settings, but these typically require ADMIN privileges to set or change.

43

Figure 3.1: PATH and PYTHONPATH system variables.

It might be simpler for users to set the variables on the command line in the Windows CMD

window. Figure 3.2 shows the command to set the PYTHONPATH prior to running a

FRANC3D Python script and prior to running the regular FRANC3D executable (where the user

will use the Python extension for crack growth).

Figure 3.2: PYTHONPATH set from the command line in a CMD window.

It should be noted that ABAQUS uses Python 2.7, and the system variable setting for the

PYTHONPATH can affect ABAQUS. Thus, we recommend that the user set the PATH on the

command line (as in Figure 3.2) or use a .bat file to first set the variables and then start

FRANC3D. In a .bat file, the command to set the PYTHONPATH is:

set PYTHONPATH=%%PYTHONPATH%%;C:\bruce\Python-2.7.14\Lib

When ABAQUS runs, it will see this setting and give a warning, but continue running:

44

executing: C:\SIMULIA\Commands\abaqus.bat

ABAQUS Warning: Recursive loop detected when expanding environment variables:

PYTHONPATH = %PYTHONPATH%;C:\bruce\Python-2.7.14\Lib

Variable will be skipped.

This option for setting the PYTHONPATH will be more important when using Python 3.x with

FRANC3D, as the user will be able to set the PYTHONPATH to their Python3.x folder and

ABAQUS will ignore that setting and continue using its own Python 2.7 version.

The PATH and PYTHONPATH settings in Linux are usually defined in the user’s shell resource

file. For example, when using the bash-shell, the file .bashrc or .bash_profile in the user’s home

folder can contain lines such as:

export PYTHONPATH=$PYTHONPATH:/home/bruce/Python-2.7.14/

There are eight classes defined in the PyF3D module: 1) F3DApp, 2) FemModel, 3)

FemResults, 4) Flaw, 5) CrackGrowthData, 6) CrackStep, 7) CrackFront, and 8) FrontPoint.

Note that file names must be provided using single quoted strings. For Windows, the file path

separator is the ‘\’ character. This must be defined using two of these characters, as ‘\\’ so that

Python will process the path correctly.

3.2.1 class F3DApp

The F3DApp is a FRANC3D application object. This is the Python analog to the main

window in the GUI version. Most scripts will require an instance of this object.

constructor:

F3DApp - No arguments.

example: f3d = PyF3D.F3DApp()

methods:

All of the method examples below begin with “f3d”, which is the F3DApp object

defined above.

AutoGrowth – see Section 2.1.1

example:

45

f3d.AutoGrowth(

model_type="ANSYS",

cur_step=1,

file_name='my_model',

num_steps=4,

step_type="SCONST",


maximum_steps=4,

flags=["TRANSFER_BC","CFACE_TRACT"],

merge_tol=0.0001,

connection_type="MERGE",

executable='ANSYS172.exe',

command='"ANSYS172.exe" -b -p ansys -np 2

-i "my_model_STEP_001_full.cdb"

-o "my_model_STEP_001_full.out" ',

global_model='my_GLOBAL.cdb',

merge_surf_labels=["AUTO_CUT_SURF"],

global_surf_labels=["GLOBAL_CONNECT_SURF"],

license="ansys",

crack_face_contact=False)

CloseModel – see Section 2.1.2

example: f3d.CloseModel()

ComputeCOD – see Section 2.1.3

example: f3d.ComputeCOD(distance=0.1)

ComputeGrowthParams – see Section 2.1.4.

example: f3d.ComputeGrowthParams(sif_method=”M_INTEGRAL”)

ComputeSif – see Section 2.1.5

example: f3d.ComputeSif(sif_method=”M_INTEGRAL”,

do_therm_terms=True)

CrackTractConst – see Section 2.1.6

example: f3d.CrackTractConst(index=1,

pressure=10.0,

load_case=1)

CrackTractDelete – see Section 2.1.7

example:

46

f3d.CrackTractDelete(index=1)

CrackTractExternalDist – see Section 2.1.8

example: f3d.CrackTractExternalDist(index=1,

mesh_file=’C:\\temp\\my_dist.cdb’,

stress_file=’C:\\temp\\my_dist.str’,

load_case=1)

CrackTractSurface – see Section 2.1.9

example: f3d.CrackTractSurface(index=0,

dist=[[0,1],[0.5,4],[1,5],[1.5,2],[2,1.5]],

load_case=2,

file_name='my_RS_SURF_0.txt'))

CrackTract1DRad – see Section 2.1.10

example: f3d.CrackTract1DRad(index=0,

axis=1,

offset=[0,0,0],

dist=[[0,1],[0.5,3],[1,0]],

load_case=2))

CrackTract2DRad – see Section 2.1.11

example: f3d.CrackTract2DRad(index=0,

axis=1,

axial=[-0.5,0.0,0.5],

radial=[0.0,1.0],

dist=[[0,1,0],[1,1.25,1]],

load_case=2)

FretModelImport – see Section 2.1.12

example: f3d.FretModelImport(model_type=ANSYS,

file_name=’C:\\temp\\uncracked.cdb’,

results_files=['C:\\fretting\\fretting_rig_ls1.str',

'C:\\fretting\\fretting_rig_ls2.str'],

results_load_cases=[0,1],

contact_pair=[contact_6_6_contact_5_6],

results_option=0)

FretNucleationCycles – see Section 2.1.13

example: f3d.FretNucleationCycles()

47

FretNucleationDataImport – see Section 2.1.14

example: f3d.FretNucleationDataImport()

GrowCrack – see Section 2.1.15

example: f3d.GrowCrack(

do_therm_terms=True,

median_step=0.1,

cycles_step=1000,

front_mult=[1],

temp_radius_type="ABSOLUTE",

temp_radius=0.05,


GrowCrackFromFile – see Section 2.1.16

example: f3d.GrowCrackFromFile(file=’C:\\temp\\new_front.txt’)

GrowMergeCrack – see Section 2.1.17

example: f3d.GrowMergeCrack()

Include – see Section 2.1.18

example: f3d.Include(file=’C:\\temp\\include_file.ext’)

InsertFileFlaw – see Section 2.1.19

example: f3d.InsertFileFlaw(file=’C:\\temp\\init_crack.crk’)

InsertMultFileFlaw – see Section 2.1.20

example: f3d.InsertMultFileFlaw(

file_names=’crack_1.crk’,’crack_2.crk’)

InsertMultParamFlaw – see Section 2.1.21

example: f3d.InsertMultParamFlaw(

flaw_type=[“CRACK”,”CRACK”],

crack_type=[“EMESH”,”EMESH”],

flaw_params=[[0.1,0.1],[0.15,0.15]],

rotation_axes=[[1],[1]],

rotation_mag=[[90],[90]],

translation=[[0,0.1,1],[0,-0.15,1]],

48

radius=[0.02,0.03])

InsertParamFlaw – see Section 2.1.22

example: f3d.InsertParamFlaw()

flaw_type="CRACK",

crack_type="EMESH",

flaw_params=[0.5,0.5],

rotation_axes=[1],

rotation_mag=[90],

translation=[0,0,10],

radius=0.05)

InsertUserBdryFlaw – see Section 2.1.23

example: f3d.InsertUserBdryFlaw(

points=[[3.642,5.0,10.054],\+

[3.645,5.0,9.984],\+

[3.650,5.0,9.910],\+

[3.9,5.0,10.14]],

front_flags=[1,1,1,0],

radius=0.078)

InsertUserMeshFlaw – see Section 2.1.24

example: f3d.InsertUserMeshFlaw(

flaw_type="CRACK",

mesh_file='surf_mesh_half_penny.cdb',

front_groups=["CRACK_FRONT"],

rotation_axes=[1],

rotation_mag=[-90],

translation=[4,5,10.05],

radius=0.06)

MapState – see Section 2.1.25

example: f3d.MapState()

OpenFdbModel – see Section 2.1.26

example: f3d.OpenFdbModel(file_name='C:\\cube\\crack_cube.fdb')

OpenMeshModel – see Section 2.1.27

example: f3d.OpenMeshModel(model_type="ANSYS",

file_name='C:\\cube\\cube_cutout.cdb',

49

global_name='C:\\cube\\cube_GLOBAL.cdb')

ReadFullGrowthHist – see Section 2.1.28

example: f3d.ReadFullGrowthHist(

file_name='C:\\cube\\cracked_cube_history.fcg')

ReadGrowthParams – see Section 2.1.29

example: f3d.ReadGrowthParams(

file_name='C:\\cube\\cracked_cube_history.fcg')

ReadResponse – see Section 2.1.30

example: f3d.ReadResponse(

file_name='C:\\cube\\cracked_cube.dtp')

RunAnalysis – see Section 2.1.31

example: f3d.RunAnalysis(

model_type="ANSYS",

file_name='static.fdb',

flags=["TRANSFER_BC",

"CFACE_TRACT","NO_CFACE_CNTCT"],

merge_tol=0.0001,

connection_type="MERGE",

element_series_type="SOLID_185_187",

executable='ANSYS172.exe',

command='"ANSYS172.exe" -b -p ansys -np 2

-i "static_full.cdb"

-o "static_full.out"',

global_model='cube_GLOBAL.cdb',

merge_surf_labels=["AUTO_CUT_SURF"],

global_surf_labels=["GLOBAL_CONNECT_SURF"],

license="ansys",

crack_face_contact=False)

SaveFdbModel – see Section 2.1.32

example: f3d.SaveFdbModel(file_name=’C:\\temp\\my_model.fdb’,

mesh_file_name=’C:\\temp\\my_model.cdb’,

rslt_file_name=’C:\\temp\\my_model.dsp’,

analysis_code=”ANSYS”)

SaveGrowthParams – see Section 2.1.33

example:

50

f3d.SaveGrowthParams(file_name=’C:\\temp\\my.cgp)

SaveMeshModel – see Section 2.1.34

example: f3d.SaveMeshModel(file_name=’C:\\temp\\my_model.cdb’,

model_type=”ANSYS”)

SetEdgeParameters – see Section 2.1.35

example: f3d.SetEdgeParameters(do_planar_seed=True,

planar_angle=178,

planar_facets=5)

SetGrowthParams – see Section 2.1.36

example:

f3d.SetGrowthParams(

growth_type="QUASI_STATIC",

load_step_map=["VERSION: 1","MAX_SUB: 2",

"0 0","0 0","LABELS: 2",

"2 Load Step 2",

"1 Load Step 1"],

kink_angle_strategy="MTS",

quasi_static_n=2,

quasi_static_loads=["NUM_STEPS: 2",

"1 FINAL 1 1 0",

"2 FINAL 1 1 0"])

SetLoadSchedule – see Section 2.1.37

SetMeshingParameters – see Sections 2.1.38

example:

f3d.SetMeshingParameters( do_surface_refinement=True,

max_vol_restarts=3)

SetPrevMeshTool – see Sections 2.1.39

SetStatusFile – see Sections 2.1.40

SetTrimRegions – see Sections 2.1.41

example: f3d.SetTrimRegions(regions=[3])

SetUnits – see Sections 2.1.42

example: f3d.SetUnits(

51

model_length="MM",

model_stress="MPA",

temperature="C")

SetUserExtensionsFile – see Sections 2.1.43

example: f3d.SetUserExtensionsFile(

file_name='user_python.py',

flags=["USER_INITIALIZE",

"USER_NEW_POINT",

"USER_KINK_ANG"])

SetWorkingDirectory – see Sections 2.1.44; for Windows the path separator is \\

example: f3d.SetWorkingDirectory(

directory='C:\\bruce\\ansys\\ansys_with_temp_mat')

SifHistory – see Sections 2.1.45

example:

f3d.SifHistory ()

StartRecording – writes the subsequent Python commands to a py_session.log file

example:

f3d.StartRecording ()

- this could be used if a user writes a complicated Python script and wants

to record the commands in a session log to play back in the GUI later

Submodeler – see Sections 2.1.46

example: f3d.Submodeler( model_type="ANSYS",

orig_file_name='cube.cdb',

submodel_file_name='cube_LOCAL.cdb',

global_file_name='cube_GLOBAL.cdb',

elem_file_name='cube_RETAINED_ELEMS.txt')

WriteCOD – see Sections 2.1.47

example:

f3d.WriteCOD(file_name=’sif_data.sif’

flags=[“TAB”,”COD”,”CSD”,”CRD”,”PNT”])

WriteCrackData – see Sections 2.1.48

example:

f3d. WriteCrackData(file_name=crack_info.dat’)

WriteFatigueData – see Sections 2.1.49

52

WriteGrowthParams – see Sections 2.1.50

example:

f3d.WriteGrowthParams()

WriteSERR – see Sections 2.1.51

WriteSif – see Sections 2.1.52

example:

f3d.WriteSifs(file_name=’sif_data.sif’

flags=[“TAB”,”XYYY”,”KI”,”KII”,”KIII”])

WriteSifPath – see Sections 2.1.53

WriteSifHistory – see Sections 2.1.54

WriteStdTempData – see Sections 2.1.55

example:

f3d.WriteStdTempData(file_name=’template_info.dat’)

The following methods do not have command line equivalents. They are implemented to

support the ABAQUS interface where FRANC3D commands are called directly from ABAQUS

CAE.

GetCrackData – returns CrackGrowthData object

example:

cgd = f3d.GetCrackData()

GetFemModel – returns FemModel object

example:

fem = f3d.GetFemModel()

GetFemResults – returns FemResults object

example:

fem = f3d.GetFemResults()

InsertMemFlaw – inserts flaw object

example:

f3d.InsertMemFlaw(flaw)

OpenMeshMemModel – processes mesh information into a FemModel object

example:

fem = f3d.OpenMeshMemModel(fem)

ReadMemResponse – processes FE results into a FemResults object

53

example:

f3d.ReadMemResponse(res)

3.2.2 class FemModel

The FemModel class stores the FE model data.

constructor:

FemModel() - arguments.

example: fem = PyF3D.FemModel()

methods:

Clear – clears the database

example: fem.Clear()

AddNode – add a node to the database

parameters: id – integer

coordinates – Vec3D

example: fem.AddNode(1,Vec3D.Vec3D(0.0,1.0,2.0))

AddElem – add an element to the database


material id – integer

coordinate system id – integer

element type – string

TET_4 TET_10 PYRAMID_5 PYRAMID_13

WEDGE_6 WEDGE_15 BRICK_8 BRICK_20 BRICK_8

54

node list – [integer,integer,…]

example: fem.AddElem(1,1,1,”BRICK_8”,[1,2,3,4,5,6,7,8])

AddMatProps – add a material to database


mat – integer

example: fem.AddMaterial(1,0)

AddBc –


entity – string

NODE ELEMENT NODE_GROUP ELEMENT_GROUP face – int (if entity is ELEMENT)

type – string

UX UY UZ FX FY FZ MX MY MZ CPRESS VPRESS TRACT BF TEMP value – integer

load case – integer

example: fem.AddBc(1,”NODE”,”UX”,0.0,1)

AddNodeSet – add a group of nodes or elements to the database

parameters: label – string

55

entity list – [integer,integer,…]

example: fem.AddNodeSet(“test_group”,[1,2,4,8])

AddElementSet – add a group of nodes or elements to the database


entity list – [integer,integer,…]

example: fem.AddElementSet(“test_group”,[1,2,4,8])

AddCoordSys – add a coordinate system to the database


angles – Vec3D

example: fem.AddCoordSys(“test_cs”,[0.,90.,0.])

AddBcCase – add a load case to the database


example: fem.AddBcCase(1)

HasNode – tests whether a node exists in the database; returns True or False


example:

status = fem.HasNode(1)

HasElem – tests whether an element exists in the database; returns True or False


example:

status = fem.HasElem(1)

56

HasMatProps – tests whether a material exists in the database; returns True or False


example:

status = fem.HasMat(1)

HasBc – tests whether a boundary condition exists in the database; returns True or False


entity – string (see AddBc)

type – string (see AddBc)

example:

status = fem.HasBc(1,”NODE”,”UX”)

HasNodeSet – tests whether a node set exists in the database; returns True or False


example:

status = fem.HasNodeSet(“test”)

HasElementSet – tests whether an element set exists; returns True or False


example:

status = fem.HasElementSet(“test”)

HasCoordSys – tests whether a coordinate system exists; returns True or False


example:

status = fem.HasCoordSys(1)

HasBcCase – tests whether a load case exists in the database; returns True or False


example:

status = fem.HasBcCase(1)

57

GetNode – get node from database


example:

nd = fem.GetNode(1)

GetElem – get element from database


example:

el = fem.GetElem(1)

GetMatProps – get material properties from database


example:

mat = fem.GetMat(1)

GetBc – get boundary condition from database


entity – string (see AddBc)

type – string (see AddBc)

example:

bc = fem.GetBc(1,”NODE”,”UX”)

GetNodeSet – get node set from database


example:

ns = fem.GetNodeSet(“test”)

GetElementSet – get element set from database


example:

es = fem.GetElementSet(“test”)

58

GetCoordSys – get node from database


example:

cs = fem.GetCoordSys(1)

GetNodeIterator – get node iterator

example:

ni = fem.GetNodeIterator()

GetElemIterator – get element iterator

example:

ei = fem.GetElemIterator()

GetMatPropsIterator – get material iterator

example:

mi = fem.GetMatPropsIterator()

GetBcIterator – get boundary condition iterator

example:

bci = fem.GetBcIterator()

GetNodeSetIterator – get node set iterator

example:

nsi = fem.GetNodeSetIterator()

GetElemSetIterator – get element set iterator

example:

esi = fem.GetElemSetIterator()

GetCoordSysIterator – get coordinate system iterator

example:

csi = fem.GetCoordSysIterator()

GetBcCaseIterator – get load case iterator

example:

bcsi = fem.GetBcCaseIterator()

GetNumNode – returns the total number of nodes

example:

nn = fem.GetNumNode()

GetNumElem – returns the total number of elements

example:

59

ne = fem.GetNumElem()

GetNumMatProps – returns the total number of materials

example:

nm = fem.GetNumMatProps()

GetNumBc – returns the total number of boundary conditions

example:

nbc = fem.GetNumBc()

GetNumNodeSet – returns the total number of node sets

example:

nns = fem.GetNumNodeSet ()

GetNumElemSet – returns the total number of element sets

example:

nes = fem.GetNumElemSet ()

GetNumCs – returns the total number of coordinate systems

example:

ncs = fem.GetNumCs()

3.2.3 class FemResults

The FemResults class stores the FE results data. By default, load case 0 is added when the

object is created.

constructor:

FemResults()

example: fres = PyF3D.FemResults()

methods:

Clear – clear the database

example: fres.Clear()

60

AddScalarResults – add a scalar result to database


entity – string

NODE ELEMENT type – string

TEMP value – integer


example: fres.AddScalarResults(1,”NODE”,”TEMP”,20.0,1)

AddVectorResults –


entity – string


DISP FORCE value – Vec3D


example: fres.AddVectorResults(1,”NODE”,”DISP”,Vec3D,1)

AddScalarList – add a list of scalar results

AddVectorList – add a list of vector results

HasResults – determine if database contains results; returns True or False


entity – string


TEMP … load case – integer

example: fres.AddHasResults(1,”NODE”,”TEMP”,1)

61

GetScalarResults – returns scalar result


entity – string


TEMP load case – integer

example: fres.GetScalarResults(1,”NODE”,”TEMP”,1)

GetVectorResults – returns vector results


entity – string


DISP FORCE load case – integer

example: fres.GetVectorResults(1,”NODE”,”DISP”,1)

GetScalarList – returns list of scalar results

GetVectorList – returns list of vector results

3.2.4 class Flaw

The Flaw class stores parametric flaw data.

constructor:

Flaw()

example: flaw = PyF3D.Flaw()

methods:

Save – saves the flaw data to a file

62

parameters: file_name – string

example: flaw.Save(”crack_data.crk”)

3.2.5 class CrackData

The CrackData class stores the crack growth data.

constructor:

CrackData()

example: cgd = PyF3D.CrackData()

methods:

Step – returns the list of crack growth steps

example: cgd.Step()

StartPoint – returns the crack start point or origin

example: cgd.StartPoint()

StartLength – returns the initial crack length

example: cgd.Startlength()

3.2.6 class CrackStep

The CrackStep class stores the crack growth data per step.

constructor:

CrackStep()

63

example: cgs = PyF3D.CrackStep()

methods:

Front – returns the crack front

example: cgs.Front()

Name –

UserIndx –

ExtensionAmount –

3.2.7 class CrackFront

The CrackFront class stores the crack growth data per front.

constructor:

CrackFront()

example: cgf = PyF3D.CrackFront()

methods:

Point – returns list of front points

example: cgf.Point()

Id – returns the crack front ID

example: cgf.Id()

StartPoint – returns the start point coordinates of the crack front

example: cgf.StartPoint()

StopPoint – returns the end point coordinates of the crack front

64

example: cgf.StopPoint()

FitFront – returns the list of fitted points to the new front

example: cgf.FitFront()

FitOldFront – returns the current front points corresponding to the new fitted points

example: cgf.FitOldFront()

FitExtensions – returns the list of extensions between the current and new front points

example: cgf.FitExtensions()

ExtensionMult – returns the extension multiplier

example: cgf.ExtensionMult()

3.2.8 class FrontPoint

The FrontPoint class stores the crack growth data per crack front point.

constructor:

FrontPoint()

example: fp = PyF3D.FrontPoint()

methods:

K – returns the SIF values at the point along the crack front for the first load case

example: fp.K()

J – returns the J-integral values at the point along the crack front for the first load case

65

example: fp.J()

T – returns the T-stress value at the point along the crack front for the first load case

example: fp.T()

G – returns the G (strain energy release rate) at the point along the crack front

for the first load case

example: fp.G()

COD – returns the crack opening displacements at the point along the crack front

for the first load case

example: fp.COD()

Temp – returns the tempaerature at the point along the crack front for the first load case

example: fp.G()

NPos – returns the normalized position at the point along the crack front

example: fp.NPos()

Coord – returns the coordinate of the point along the crack front

example: fp.Coord()

Axes – returns the local axes at the point along the crack front

example: fp.Axes()

KinkAngle – returns the crack growth kink angle at the point along the crack front

example: fp.KinkAngle()

Extension – returns the crack extension at the point along the crack front

66

example: fp.Extension()

NodeId – returns the node ID of the point along the crack front

example: fp.NodeId()

ElemId – returns the element ID for the point along the crack front

example: fp.ElemId()

67

4. Python Crack Growth Extensions

The FRANC3D options for crack growth can be extended by using user-supplied subroutines

written in the Python programming language.

FRANC3D predefines the names of the user-supplied subroutines. To simplify managing user

defined subroutines, they should all be placed in one .py file. FRANC3D reads the .py file and

searches for the predefined routine names.

The user defined Python subroutine names that FRANC3D currently recognizes and a short

description follows:

def on_initialize() – This function is called once before any other user extensions are called. It

primarily is used to initialize any global variables used by other functions.

def on_kink_angle() – During crack growth, this function is called once for each crack-front

point on each crack front. The purpose of the function is to compute the “kink” angle (deviation

from planar growth), which determines the direction of crack growth. The extension for this

direction is computed using one of the algorithms built into FRANC3D. The function is not

passed any arguments; data needed to compute a new crack-front coordinate is obtained using

the predefined data access routines described below. The function should return a scalar value,

which is the kink angle in radians.

def on_new_point() – During crack growth, this function is called once for each crack-front point

on each crack front. The purpose of the function is to compute the polar coordinates of a

corresponding point on a new (extended) crack front. The new point lies in the plane that is

perpendicular to the crack front at the current crack front point. The function is not passed any

arguments; data needed to compute a new crack-front coordinate is obtained using the predefined

data access routines described below. The function should return two scalar values, the crack

extension and the kink angle in radians, in that order. The algorithms built into FRANC3D for

computing kink angle can be accessed using routines described below.

def on_cycles_growth_rate(DK,R,temp) – This function allows a user to define a crack growth

rate for a material due to cyclic fatigue loading (e.g. da/dN). It is passed the stress intensity

factor range (DK = Kmax – Kmin), the stress ratio (R = Kmin / Kmax), and the local temperature. The

function should return the crack extension per load cycle.

def on_time_growth_rate(K,temp) – This function allows a user to define a crack growth rate for

a material as a function of time (e.g. da/dt). It is passed the stress intensity factor and the local

temperature. The function should return the crack extension per unit time increment.

def on_start_step() – This function is called at the beginning of each crack growth step and

allows one to set values for global variables used to compute crack extensions for the step. It is

not passed any arguments and does not return any values.

68

def on_end_step() – This function is called at the end of each crack growth step. It is not passed

any arguments and does not return any values.

4.1 Data Access Functions

To implement the user functions described above, it might be necessary to access data in the

FRANC3D crack database. The following functions are predefined in the user Python

environment, and can be called to access crack data.

NumCrackSteps() – returns the number of crack growth steps in the current model. Use the

SetCrackStepNum function to set the current crack step to a specified step.

NumCrackFronts() – returns the number of crack fronts for the current crack step. Use

SetCrackFrontNum function to set the current crack front to a specified front for the current

crack step.

NumCrackPoints() – returns the number of crack front points for the given step an crack front.

Use the SetCrackIndexNum function to set the crack front point ID for the current crack front

and crack step.

NumLoadSteps() – returns the number of load steps.

NumLoadSubsteps(load_step) – returns the number of sub steps for the given load step.

GetCrackStepNum() – returns the current crack step number.

GetCrackFrontNum() – returns the current crack front number.

GetCrackIndexNum() – returns the index of the current point on the crack front.

GetNPos() – returns the normalized crack front coordinate of the current crack front point.

GetCoord() – returns the Cartesian coordinates of the current crack front point as a Vec3D.

GetXAxis() – returns the direction cosines of the x-axis of the local crack front coordinate

system relative to the global Cartesian coordinates as a Vec3D.

GetYAxis() – returns the direction cosines of the y-axis of the local crack front coordinate

system relative to the global Cartesian coordinates as a Vec3D.

GetZAxis() – returns the direction cosines of the z-axis of the local crack front coordinate system

relative to the global Cartesian coordinates as a Vec3D.

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GetK([step[,sub step]]) – returns stress intensity factors (modes I, II, and III) as a Vec3D. If no

arguments are given, the K’s for load step 1 are returned. If no sub step argument is given, the

K’s for the final (or only) sub step are returned.

GetT([step[,sub step]]) – returns a T-stress (if available). If no arguments are given, the T for

load step 1 is returned. If no sub step argument is given, the T for the final (or only) sub step is

returned. None is returned if the T-stress is not available.

GetJ([step[,sub step]]) – returns a J-Integral value. If no arguments are given, the J for load step

1 is returned. If no sub step argument is given, the J for the final (or only) sub step is returned.

GetG([step[,sub step]]) – returns energy release rates (modes I, II, and III) as a Vec3D. If no

arguments are given, the G’s for load step 1 are returned. If no sub step argument is given, the

G’s for the final (or only) sub step are returned. None is returned if G’s are not available.

GetCOD([step[,sub step]]) – returns crack opening displacements (modes I, II, and III). If no

arguments are given, the COD’s for load step 1 are returned. If no sub step argument is given,

the COD’s for the final (or only) sub step are returned. None is returned if COD’s are not

available.

GetTemp([step[,sub step]]) – returns a crack-front temperature. If no arguments are given, the

temperature for load step 1 are returned. If no sub step argument is given, the temperature for

the final (or only) sub step are returned. None is returned if temperatures are not available.

GetDcPoint() – returns the coordinates of the points used to evaluate displacement correlation

stress intensity factors as a Vec3D.

Maximize(x_start,x_stop,func,data) – Finds the value of x in the range x_start – x_stop that

maximizes the user supplied function func. The function is passed the current x and the data (i.e.

my_func(x,data)).

SetCrackStepNum(step) – used to set the crack growth step number. This is used to access data

(K’s, coordinates, etc.) for steps other than the current crack step.

SetCrackFrontNum(front) – used to set the crack front number. This is used to access data (K’s,

coordinates, etc.) for fronts other than the current crack front.

SetCrackIndexNum(index) – used to set the crack point index. This is used to access data (K’s,

coordinates, etc.) for crack-front points other than the current point.

MtsKinkAngle(Kvec) – returns a kink angle computed by the maximum tensile stress (max hoop

stress) criterion. The argument is the KI, KII, and KIII values either as Vec3D or a sequence of

three floats

MssKinkAngle(Kvec,eta_II,eta_III) – returns a kink angle computed by the maximum shear

stress criterion. The first argument is the KI, KII, and KIII values either as Vec3D or a sequence of

70

three floats. The second and third arguments are parameters used to weight the mode II and

mode III. The maximum shear stress kink criterion is the direction is

max hIIKII

r (q )( )2

+ hIIIKIII

r (q )( )2æ

èçö

ø÷ ,

where Kr is the resolved stress intensity factors in the direction.

GeneralKinkAngle(Kvec,eta_II,eta_III) – computes the kink angle by both the maximum tensile

stress and maximum shear stress criteria, and returns a kink angle associated with the greater

resolved stress intensity factor of the two. The first argument is the KI, KII, and KIII values either

as Vec3D or a sequence of three floats. The second and third arguments are parameters used to

weight the mode II and mode III.

SerrKinkAngle(Kvec,eta_II,eta_III) – computes the kink angle by a maximum strain energy

release rate criterion. The first argument is the KI, KII, and KIII values either as Vec3D or a

sequence of three floats. The second and third arguments are parameters used to weight the

mode II and mode III. The maximum strain energy release rate kink criterion is the direction is

max KI

r (q )2 + hIIKII

r (q )( )2

+ hIIIKIII

r (q )( )2( )

,

where Kr is the resolved stress intensity factors in the direction.

Vec3D(e1,e2,e3) – is a predefined class that stores a vector of 3 values. Individual components

can be accessed like a list (e.g. Kvec = GetK() ; KII = Kvec[1]). In addition, most common

arithmetic operations (addition, subtraction, scalar multiplication, scalar division, inner product,

etc.) are defined for Vec3D’s

4.2 Specifying a user extension file

Before any user python extensions can be used, the file containing the python code must be read

into FRANC3D. Under the Advanced menu, select the Read User Extensions… option. After

selecting the .py file FRANC3D scans the file to find which user extensions are defined in the

file. It then displays the dialog shown below, which give one the option turn on or off defined

functions.

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4.3 Example user extension files

This example implements a crack growth extension based on a Paris type model where the C

coefficient is a linear function of the temperature. It calls a built-in function to compute the kink

angle. This example was written for Python 2.7.

# =====================================================================

# User defined crack extension function:

#

# This version computes an extension based on a temperature dependent

# Paris model for a specified number of cycles.

# =====================================================================

# ---------------------------------------------------------------------

# initialization function

# ---------------------------------------------------------------------

def on_initialize():

global C_b, C_m, n, cycles

C_b = 100.0

C_m = 10.0

n = 3

cycles = 1000.0

return

# ---------------------------------------------------------------------

# crack extension function

# ---------------------------------------------------------------------

def on_new_point():

global C_b, C_m, n, cycles

C = C_m * GetTemp() + C_b

dadN = C * GetK()[0]**n

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angle = MtsKinkAngle(GetK()[0])

return dadN * cycles, angle

This example implements the maximum tensile stress kink angle criterion. The maximum tensile

stress criterion is built-in to FRANC3D, but this example shows how it could be done as a user

extension.

# =====================================================================

# User defined kink angle function:

#

# This version computes the Max Tensile Stress criterion

# for the sum of the K's from all load cases

# =====================================================================

import math

# ---------------------------------------------------------------------

# function to compute the hoop stress

# ---------------------------------------------------------------------

def hoop_stress(theta,Ksum):

KIf = Ksum[0] * (math.cos(theta/2) * (1.0-math.sin(theta/2)**2))

KIIf = 0.75 * Ksum[1] * (math.sin(theta/2) + math.sin(3*theta/2))

return KIf - KIIf

# ---------------------------------------------------------------------

# kink angle function

# ---------------------------------------------------------------------

def on_kink_angle():

# compute the sum of the K's for all load steps (note

# load steps are numbered from 1 to n

Ksum = Vec3D(0,0,0)

for i in xrange(NumLoadSteps()) : Ksum += GetK(i+1)

# call the F3D builtin Maximize function to find the

# angle where the hoop stress is maximum

max_ang = Maximize(-math.pi/2,math.pi/2,hoop_stress,Ksum)

return max_ang

This example implements the computation of a new crack front point where the kink angle

determined by the maximum tensile stress criterion and the crack extension is computed using a

Paris model.

# =====================================================================

# User defined new point function:

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#

# This version computes a new crack front point location

# base on a max hoop stress angle criterion and an assumed

# Paris like growth model

# =====================================================================

import math

# ---------------------------------------------------------------------

# function to compute the hoop stress

# ---------------------------------------------------------------------

def hoop_stress(theta,Ksum):

KIf = Ksum[0] * (math.cos(theta/2) * (1.0-math.sin(theta/2)**2))

KIIf = 0.75 * Ksum[1] * (math.sin(theta/2) + math.sin(3*theta/2))

return KIf - KIIf

# ---------------------------------------------------------------------

# new point function

# ---------------------------------------------------------------------

def on_new_point():

# compute the sum of the K's for all load steps (note

# load steps are numbered from 1 to n

Ksum = Vec3D(0,0,0)

for i in xrange(NumLoadSteps()) : Ksum += GetK(i+1)

# call the F3D builtin Maximize function to find the

# angle where the hoop stress is maximum

angle = Maximize(-math.pi/2,math.pi/2,hoop_stress,Ksum)

# compute an exention based on a Paris like model

extend = 0.001 * Ksum[0]**3.2

return extend, angle

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